<!DOCTYPE html>
<html>
    <head>

        <style>
            header{
                height: 5rem;
                background-color: rgb(255, 88, 88);
            }

            main section:first-child{
                float: left;
                width: 300px;
                background-color: aqua;
                height: 500px;
            }

            main :nth-child(2){
                float: right;
                background-color: #eee;
                width: 300px;
                height: 500px;
            }
            main section:last-child{
                margin-left: 310px;
                margin-right: 310px;
                background-color: antiquewhite;
                /* height: 500px; */
            }
            /* main::after{
                content: "";
                display: block;
                clear: both;
            } */

            /* main{overflow: hidden;} */
            
            footer{
                background: rgb(255, 75, 75);
                height: 3rem;
                overflow: hidden;
                width: 100%;
            }
        </style>
    </head>
    <body>
        <header></header>
        <main>
            <section>123</section>
            <div>12asgggggggggg</div>
            <section>124</section>
        </main>
        <footer></footer>
    </body>
</html>